Hướng dẫn cách sử dụng máy toàn đạc điện tử Topcon GTS 235

Topcon GTS-235 Total Station Guide Jerry Davis, San Francisco State University IGISc This guide is intended for using SFSU Institute for Geographic Information Science Topcon GTS-235 total station (TS) to measure coordinates and recording the values in a data collector First, a checklist to make sure you have everything you need: Topcon FC-100 Data Collector with case USB cable* Compass (if you want to set up backsight to azimuth) Prism + holder (in accessories pack) Serial cable (data collector to TS) The TS uses the abbreviation NEZ (“Northing Easting Z”) for coordinates – Some background: BC-27 this is the same as UTM, but remember that Northing comes before Easting,Topcon in contrast to battery X charger, output 9V, 1.8 A.* AC/DC converter (for coming before Y in standard Cartesian parlance charging data collector) Power cord for battery Topcon AD-9B Output use the to measure coordinates, you must establish: charger 12V To 1000mA, + TS center.* The Occupied Point, where the TS is set up This is either done by: a centering the instrument over a known point (like a benchmark), and Raincover entering the data Topcon GTS-235 & cloth b resecting to or more known points using distance, thus requiring the rod-mounted target (has removable battery & tribrach) Range pole with integrated prism is held at those points level & standard c resecting to or more known points using angles, like distant visiblebubble landmarks Plummet (plumbob) 5/8"-thread brass mount for A backsight to set the azimuth It doesn’t use a compass, so initially it sets whichever prism holder direction it’s looking to be 0° or north If you have the Occupied Point established in the TS, Lens cap the backsight point will be used to accurately set the azimuth If you use resection, the Case (holds everything backsight is not required A flat-top tripod, either except data collector, wooden or aluminum, prism/rangepole assembly, After are established, readings are in the same coordinate system as thetripod, pointsUSB used Make with these 5/8"-threaded cable & suremounting you are screw reading in meters if the coordinate system is UTM If done right, this isconverter much more AC/DC for data accurate than using a compass to establish the backsight direction collector) * parts not needed in the field (battery chargersdirections step you through how to set up the instrument, thenNot shown: The following how to set tool the kit with and USB cable) jeweller's screwdriver, hex occupied point and backsight, then how to get readings to record key, hook, adjustment pins and brush Parts to carry: Yellow case with total station, serial cable, plumbob, raincover, BC-27 battery charger for total station, power cord, tool kit Tamrac accessories pack with prism, data collector, USB cable, AD-9B AC/DC, and prism holder (shown in blue italics above and on next page) Range pole with 5/8" mount Flat-top tripod Version 1/11/2009 Topcon Total Station Accessories Pack (Tamrac digital camera bag) Prism Topcon FC-100 Data Collector Topcon AD-9B AC/DC Converter Output DC12v 1000 mA center positive space for compass, tools, etc in pockets: • Prism rangepole mount (shown here) • USB cable Other things you'll probably need: • survey pins for instrument locations and temporary benchmarks • hammer • survey tape (for instrument height, other measurements) • rebar (for monumenting if needed) Instrument Setup Make sure tripod legs are securely tightened and well set into ground surface, and that upper mounting plate is as level as possible before mounting instrument On sloping ground, have one leg upslope Carefully mount the instrument with the screw from the tripod If you are going to occupy a benchmark, position the instrument as near as possible over the benchmark; you should use the plumbob to get it close (within a centimeter or so) – you'll be able to get it closer after leveling using the laser plummet You should remove the plumbob before continuing Packing the Total Station The total station is a sensitive instrument When packing the total station in the case, make sure to unlock the horizontal and vertical controls so they turn freely Version 1/11/2009 2 Identify the components you need to use: a) The tribrach at the base, which contains three leveling screws and a circular bubble for coarse leveling There's also a lock which you can undo to release the tribrach, but you won't need to this b) Two identical LCD display units with: • Power • Menu • Escape • Enter rough sighting collimator battery Lens side of telescope Vertical controls Horizontal controls • Star • NEZ coordinate mode • Horizontal distance mode • Angular measurement mode Display Laser plummet Tribrach with leveling screws Horizontal & Vertical Controls • • left-right and up-down Function vertical: motion clamp tangent screw buttons used for menu choices c) A sighting telescope with eyepiece and lens horizontal: sides Focus is the outermost brown circle, with motion clamp the cross-hair focus the tiny black ring around tangent screw the eyepiece Above the telescope is a rough sighting collimator with a triangle visible inside d) Horizontal and vertical control knobs: larger motion clamps which are loosened for free movement and coarse adjustment, and tightened for fine adjustments with the tangent screw, mounted on the motion clamp Located beside and above one of the display units and to the lower left of the telescope lens If it's on the eyepiece side, loosen the vertical motion clamp and rotate the telescope 180° to get the lens on the clamp side – this is called the direct reading, and is required for the data collector to work e) Plate bubble level, mounted above one of the displays f) A battery in the post to the left of the vertical control The battery can be released with a button on the top g) There are other parts like the laser plummet you shouldn't mess with, and signal and power ports which you'll use later Check the battery level You need to charge it before using it Version 1/11/2009 3 Coarse-level the instrument using the bubble level on the tribrach Tip: Start by positioning yourself in line with one of the adjustment knobs (C), with the other two knobs (A & B) forming a perpendicular (see figure below) Then simultaneously adjust A & B to tilt the instrument to the left or right; always turn them together either in or out from your perspective – you'll be turning the knobs in opposite directions, but think in or out Once centered left to right, use the third knob C independently to center the bubble front to back You may have to the left-right centering again, etc You can also this with one knob (C) towards you AA C C C forward B AA B In: tilt left Out: tilt right (bubble right) (bubble left) AA backward B Fine-level the instrument Use the 30" (30 seconds of angle) plate level above one of the LCD displays to a fine adjustment You'll use the same adjustment knobs, but you will need to (loosen the horizontal motion clamp and) rotate the instrument parallel to the leftright axis, then parallel to the front-back axis, to each of those adjustments You'll notice that the adjustment is very sensitive, requiring tiny movements, and the bubble moves slowly to its stable reading – wait seconds for it to adjust each time before you adjust any more Check the level in all four directions by rotating 90° each time If your tripod is not mounted on stable ground, you'll never get it leveled If occupying a benchmark, reposition over the benchmark using the laser plummet Note: One method that may make it easier to position over the benchmark is to remove the instrument from the tribrach while positioning the tribrach over the point Since it's locked, you'll need to unlock it by first using the small screwdriver in the toolkit to undo the safety on the lock, then unlocking and removing the instrument (carefully) a) Power up the display Wait a few seconds for the initial and contrast settings to display, followed by the normal angle mode display (V and HR values displayed) b) Press the star key to get to the star menu, and select the laser plummet with F4 The laser plummet will then illuminate a visible red dot on the ground c) Loosen the tripod screw to position the dot on the benchmark; then tighten the screw d) Turn off the laser plummet to save power Extra-fine leveling using the tilt sensor You can use the internal tilt sensor to get it leveled even better (If not already on, power the instrument up and wait for the normal angle mode display.) Use the Star menu, then F2 to select the tilt sensor Initially the X-On (F1) mode is on, which you use to make tiny adjustments to the front-back tilt – the goal is to get it within 5" of Then select XY-On (F2) to adjust the right-left From here you can also make more front-back adjustments F4 lets you check the laser plummet if you want Version 1/11/2009 How to Collimate: Point the telescope toward a bright surface, like a blank white sheet of paper held in front Adjust the diopter ring (closest to your eye) to focus the cross hairs Aim the target roughly using the sighting collimator, with the target at the peak of the triangle in the sight Focus the target with the focusing knob from Topcon GTS 230 series manual You may want to check for parallax by shifting your eye slightly when focused on a distant object (> 200 m) If it moves, adjust the diopter and focus further to eliminate parallax error What this Guide provides, and what are in other documents This Guide: Basic use for setting up the instrument with all related parts, for surveying points May be all you need, unless you need to go further or make adjustments Assumes you'll use the PDA to record data Topcon GTS 230 Series hardware manual Assumes you're not using the PDA, and also provides information on the total station parts, including checks for accuracy and adjustments Topsurv Manual Covers the software that runs on the PDA The GPS & Survey sections can be looked at for more details on setting up the survey, etc The GPS section isn't relevant so skip to page 6-1 for the survey section It covers some stuff this unit doesn't do, like scanning, that you can ignore The last section is on using the GTS for leveling Version 1/11/2009 Setting the instrument position: Option 1: Occupying a benchmark This is probably the most accurate method of re-surveying a site (See "Benchmarking and Accuracy" section) If you've positioned the instrument over a benchmark, we just need three settings established: (i) the height of the instrument; (ii) a backsight to establish direction in the coordinate system being used; and (iii) the coordinates of the benchmark Connect the Data Collector (FC-100) using the serial cable from the 9-pin port on the bottom right of the data collector to the circular 6-pin serial port on the DTS, and power it up Start TopSURV from the Windows desktop, and either select an existing job, or create a new job If you're starting a new data collection to later download, you'll probably want to create a new job Unless you know otherwise, use the default settings by pressing Finish when it appears at the top Create a benchmark point by going to Edt > Points and Add You can either give the point a new number or go with the assigned (1) If desired, set a code; the pull-down will have no existing codes, but you can create one simply by going to the entry and typing a code (like "BENCHMARK" or "THALWEG" or something), then you'll have that code available later as a pull-down selection Enter the N (northing) E (easting) & Z (elevation) for the benchmark Ok out of this point, and close the Points dialog to get back to the main menu Use the Srv menu to get to Occ/BS Setup Then select the Occ Point you just created for the benchmark Measure the HI (height of the instrument) in the same units (probably meters) of the coordinate system Remember that you are surveying from the benchmark, so the height of the instrument (HI) is important All NEZ readings will be in reference to the NEZ of the benchmark – the HI and rod height entries are used by the instrument or data collector to make this work If you later backsight to this point, the rod will be positioned on the benchmark You might want to see if the numbers make sense Forgetting to enter the correct HI or rod height will create a serious blunder in Z values Consider what kind of backsight source you have The possibilities are: b You know the true azimuth to some observable feature You're only likely going to have that if you use a compass (corrected to true azimuth with the known magnetic declination.) In this case, you'll use enter this in the BS Azimuth field (the button toggles with BS Point) Note that compasses are only accurate to about a degree c You know the coordinates of distant features like mountaintops, tv broadcast towers, etc – too far away to occupy with the rod & reflector In this case, you'll use BS Point with Measure dist to BS unchecked (if doing multiple readings to check accuracy, you'll need to set its Meas Type to HA/VA, which you'll find in its settings.) d You know the coordinates of nearby features that you can occupy with the rod & reflector You'll check Measure dist to BS, or for multiple readings set Meas Type to HA/VA/SD Use either BS Azimuth or BS Point (more likely) to set the horizontal circle to true azimuths If you have multiple points, use these to verify accuracy Version 1/11/2009 BS Azimuth option: If you don't have a second benchmark to sight to, but you have the azimuth of a visible feature to sight to (maybe established with a compass), toggle to BS Azimuth and enter the azimuth as DDD.MMSS (thus 206°34'08" is entered as 206.3408.) Use coordinate system azimuths, so if you're using a compass for this, you'll need to know the magnetic declination and the coordinate system declination to enter the correct value Then use the button in the lower right to Measure the BS Note the BSCircle will display the reading from the TS, while the azimuth will match the new setting Recommendation: Change the BS Circle to read the same as the BS Azimuth by using its menu to Set to Az, then transfer this to the total station with HC Set This allows you to read azimuths directly, and it may make it easier to later re-establish the backsight Problem with Using a Compass for Backsight Even if you adjust for magnetic declination, a  compass will only be accurate to about a degree.   The total station will then still be able to derive  much more accurate angular readings, but they  will all be off by the same amount as the compass  reading was off.  Your map will be accurate  geometrically and it should look ok since its  orientation to north should be as close as the  compass gets you.  But if you try to do a repeat  survey later to measure change, using a compass  to setup the backsight, those readings will all be  off by the amount that new backsight was off.   Thus the new survey will not align accurately with  the old survey.      Notes: Alternative:  Use BS Point with fixed points  • Remember that the instrument doesn't have a compass, but instead has a highly accurate horizontal circle, that reads from whichever direction it was pointing when you turn it on, from internal memory The backsight establishes a true direction • The memory feature allows it to remember its sighting direction while at one location even if turned off and on This is handy if something goes wrong and you need to start the software over again • Recommendation: Change the BS Circle to read the same as the BS Azimuth – Use the BS Circle menu to Set to Az, then transfer this to the total station with the HC Set This allows you to read azimuths directly from the instrument display, and it may make it easier to later re-establish the backsight If you haven't moved the instrument, you may be able to enter the reading shown on the instrument into BS Azimuth, then Meas to make that equal to the BS Circle But the safest approach is to reshoot the backsight • You can sight to multiple backsights to determine accuracy and possibly re-sight individual backsights if you suspect an error Version 1/11/2009 BS Point option: If you have a points to sight to, use this option, even if you can't occupy it with the rod You must have the point entered in the point list, so this first if necessary using the method in step Re-establishing an earlier survey's above Then measure to that point occupied with the rod, coordinate framework using its distance measurement, or to distant features that If you're happy enough with the original you can see but can't occupy (with Measure dist to BS survey, and any compass-derived error unchecked, or for multiple readings set the Meas Type to isn't considered a problem, you can reHA/VA distance measurement) The instrument will derive establish that framework later if you had the azimuth vector from the two N-E coordinates established some fixed points – on permanent stable features or Where you get the coordinates for the backsight points? monumented with hammered-in rebar One source might be from a GPS survey, though you may If from your instrument location (which need to be concerned with limited accuracy Submeter you will need to have monumented for accuracy units can work for this, but even their accuracy is the repeat survey) you can sight to a not as good as you can get with the total station So think fairly distant stable feature, you can of distance as your friend As seen in the Table in the record that azimuth to use for a Benchmarking and Accuracy section, a GPS point accurate backsight when you return You'll still to 20 cm at 20 m distance has an angular accuracy of 2063" have the original compass backsight (that's 2063 seconds of arc, or 0.57°), so this would be error, but it is fixed so the surveys will better than a compass reading With a GPS point accurate overlay accurately So when you're to m, you would need to be at 500 m distance to see this planning a repeat survey, even this angular accuracy; this is beyond a reasonable sighting method should only be used to establish ranges Greater distances reach finer accuracies, though a coordinate system, and you'll need to only survey-grade GPS readings to 0.01 m come close to monument it so you can derive the ~5" accuracy of the total station repeatable coordinates which you can use for backsights Notes: • Remember that the instrument doesn't have a compass, but instead has a highly accurate horizontal circle, that reads from whichever direction it was pointing when you turn it on, from internal memory The backsight establishes a true direction • The memory feature allows it to remember its sighting direction while at one location even if turned off and on This is handy if something goes wrong and you need to start the software over again • Recommendation: Change the BS Circle to read the same as the BS Azimuth by using its menu to Set to Az, then transfer this to the total station with HC Set This allows you to read azimuths directly from the instrument display, and it may make it easier to later re-establish the backsight If you haven't moved the instrument, you may be able to enter the reading shown on the instrument into BS Azimuth, then Meas to make that equal to the BS Circle But the safest approach is to reshoot the backsight • You can sight to multiple backsights to determine accuracy and possibly re-sight individual backsights if you suspect an error Version 1/11/2009 Setting the instrument position: Option 2: Resection to two or more benchmarks Though a bit less accurate, this option has the advantage of a somewhat easier setup since the TS doesn't have to be positioned over the benchmark You can however improve accuracy if you have more than two benchmarks to sight to Note that there are two types of resection: one that only uses angles, requiring at least three benchmarks; the other using distance We'll the latter The first few steps are same as with option above Connect the Data Collector (FC-100) using the serial cable, and power it up Start TopSURV from the Windows desktop, and either select an existing job, or create a new job If you're starting a new data collection to later download, you'll probably want to create a new job Unless you know otherwise, use the default settings by pressing Finish when it appears at the top Use the Srv menu to get to Resection You'll initially see a place to put an occupied point for the instrument, but you don't have this so go to Next to get to your first benchmark to sight to If you want your derived instrument location to be used later as a benchmark, you should enter an HI value, at the measured height of the instrument above the benchmark you've created; then your saved position will be of the benchmark location below the instrument, not the actual instrument Select the point from the list, enter the rod height, and press the Meas button once you've aimed the TS at the reflector It should return with a happy sound Repeat for the next benchmark, etc Check the map to see how the points are arranged Go to the Set tab to see how well the resection worked You'll see values ('Sd' I think is standard deviation) indicating how close your readings are You can re-measure readings to see if you can improve them; you can also remove a reading by going to remeasure and exiting (not closing) back to the Set When you're happy with the results, press the Accept button to set the instrument location You'll be taken to the Store Point dialog, indicating that you want to store the instrument position Note that unless you had entered an HI value before, this position is that of the instrument itself – this works fine, unless you need to re-occupy that point as a benchmark later on Notes: • Resecting to or more points will produce an error check, and you might use this to note problematic readings • If you are resecting, typically you are not at a permanent benchmark, so the HI (height of the instrument) isn't needed The NEZ for the instrument point is at the Z for the instrument itself, not the ground beneath it It's ok to enter an HI value, but make sure you use it for both resection and foresights You might want to check the numbers you get to avoid blunders, especially in Z values Version 1/11/2009 Capturing points At this point, we'll assume that your instrument position is known and it has a backsight direction, from either of the above options Now the instrument is ready to capture new points Use Srv > Observations to start capturing points As with the point creation process, you have a minimal data dictionary to use (Perhaps you can make this more elaborate, but the basic version works for me.) The Point is initially assigned a new number, but you can change this and even mix letters or other characters If you start the id with a letter, the program will automatically use this as a prefix to increment (e.g., from 'A1' to 'A2', etc.) The Code is useful for categorizing your operations, and you can create new types on the fly: existing code types can be selected with a pull-down, or you can type in a new code, like "thalweg" One type of point you may need is the next instrument position, where you should also hammer in a benchmark Note the rod height is easily seen and altered – you may need to change the rod height in the middle of the survey to make it easier to see over brush To survey a point, sight it first, then press the Meas button It will beep a happy sound if you get a good point, then will prompt you for the HR – you don't need to change this; this just allows you to make a change if you realize it's wrong You will also be prompted for codes and such Moving the instrument While you should try to maximize the number of points measured from a given instrument setup, you will often find that you need to move the instrument to a new location The most accurate way to this is to: (1) start from a benchmarked location, using a measured and entered HI (height of the instrument); (2) survey in and establish the next position as a benchmark (either with a temporary or permanent stake); (3) move the instrument to the next position, measuring and entering its HI, and using the previous position as the backsight Exporting Data & Bringing it into a computer To export a text file of points, use Job > Export … To File … In the To File dialog, specify Data: Points, Format: Text then Next to go to a dialog for specifying a name and location (By default it goes into \CF Card\TPS TopSURV\IEFiles – but check this anyway.) Then in text file format, specify comma or tab delimited, etc You can see your file in the FC-100 by opening it in MS WordPad (to keep TopSURV running, press the windows button to get a start menu, and go to MS WordPad – when you exit it, you'll be back in TopSURV.) There are several ways of getting the data into another computer The simplest is just to plug the USB cable in, and set up Microsoft ActiveSync to use the connected device as a guest (partnerships seem unnecessary) Using the location noted for export files (probably \CF Card TPS TopSURV\IEFiles), explore for the text file you created Open in Excel to convert the tabdelimited text Remember that NEZ is essentially YXZ, not XYZ Importing Data from another computer You can basically reverse the above process to import a file of coordinates This is handy if you have known points you want to import, maybe from a GIS file You will probably want to maintain the same fields Use Job > Import to get to the right dialog Version 1/11/2009 10 Benchmarking and Accuracy Accurate surveys require good control points, especially if a study area is going to be revisited to determine change over time This is commonly needed for riparian surveys, where floods can move stream channel features To attain centimeter accuracy, benchmarks such as 4' rebar must be hammered into stable parts of the landscape But how we determine positions for these benchmarks? Local vs Global Coordinate Systems Traditional land survey methods typically use a local coordinate system, and rely on benchmarks to maintain accuracy over time These can be converted into global coordinates such as the Geographic Coordinate System (GCS) of latitude and longitude or cartesian coordinate systems based upon GCS such as UTM or state plane Critical to these is the datum system used, such as WGS84; survey manuals may refer to these global coordinates as WGS84 GPS provides global coordinates, but we must consider accuracy If we have the time, situation and equipment to derive centimeter-accuracy survey-grade GPS coordinates, we have a good way to derive global coordinates for benchmarking This is often not possible, so we're typically using submeter-accuracy GPS for benchmarking The best accuracy for these is attained through post-processing For the Trimble ProXH, we can probably get 20 cm or so accuracy, under good conditions (pretty clear sky view, right time) Position vs Angular Accuracy First we need to consider the kinds of accuracy benchmarking provides There is both vertical (elevation) and horizontal (xy coordinates) accuracy, of course, but there is also both positional and angular accuracy Positional accuracy is fairly simple – if you are off by some distance in x and y coordinates, that's your error Angular accuracy relates to position accuracy in two ways (1) If a reading by the TS is off by a given angle, the surveyed position can be off by the sine of the angle times the distance With a 5-second TS like the GTS235, the relative error this creates is rarely a concern, though the absolute angle depends on the backsight setting (2) The positions of the from and to points used for backsighting to set the HC will influence the accuracy of the HC, and thus of the positions surveyed Greater backsight distances are needed to reduce the effect of position errors on this angular setting; a simple rule of thumb is P B= M A where: B = backsight distance (distance from the instrument to the backsight point) P = backsight point accuracy A = desired survey accuracy M = maximum distance to surveyed point So for a 50-m maximum survey distance, a 20-cm backsight point accuracy from a good GPS point, to get a cm accuracy from angular settings requires 50 * 0.2/0.01 = 1000 m backsight distance For 10 cm accuracy, that would be 100 m Version 1/11/2009 11 Note that this does not avoid the effect of position accuracy for the instrument; it only avoids errors resulting from the angular HC setting If the instrument position is off by 0.2 m, after using a GPS to determine its position, then all of the points will be off by this much, in addition to any other errors This points to the need to use benchmarks for surveys needing repeating If a repeat survey depends on GPS to reestablish instrument position, the accuracy of the GPS reading limits the accuracy of the survey Recommendations So for surveys that are going to be repeated, benchmarks are going to be needed, unless GPS accuracy is sufficient for the changes expected To establish an correctly oriented coordinate system for mapping, GPS can be used for benchmarking instrument and backsight position, as long as the distance is sufficient to derive an accurate direction Use the equation on the previous page to determine this, but compare this with the accuracy of a compass (typically around 1°, or 3600 sec), which can be improved upon with at least a 20 m backsight distance, given a 20-cm GPS accuracy: Table Angular accuracy in seconds from sightings to GPS points from 0.01 to m accuracy Position accuracy from 0.01 to 5 m  dist  (m)  10  20  30  40  50  60  70  80  90  100  200  300  400  500  600  700  800  900  1000  arc (m)  from 1°  0.17  0.35  0.52  0.70  0.87  1.05  1.22  1.40  1.57  1.75  3.49  5.24  6.98  8.73  10.47  12.22  13.96  15.71  17.45  Version 1/11/2009 0.01  206  103  69  52  41  34  29  26  23  21  10  7  5  4  3  3  3  2  2  0.1  2063  1031  688  516  413  344  295  258  229  206  103  69  52  41  34  29  26  23  21  0.2  4126  2063  1375  1031  825  688  589  516  458  413  206  138  103  83  69  59  52  46  41  0.3  6189 3094 2063 1547 1238 1031 884  773  688  619  309  206  155  124  103  88  77  69  62  0.4  8253 4126 2750 2063 1650 1375 1179 1031 917  825  413  275  206  165  138  118  103  92  83  0.5  10318 5157 3438 2578 2063 1719 1473 1289 1146 1031 516  344  258  206  172  147  129  115  103  0.6  12383 6189  4126  3094  2475  2063  1768  1547  1375  1238  619  413  309  248  206  177  155  138  124  0.7  14450 7221 4813 3610 2888 2406 2063 1805 1604 1444 722  481  361  289  241  206  180  160  144  0.8  16519 8253 5501 4126 3300 2750 2357 2063 1833 1650 825  550  413  330  275  236  206  183  165  0.9  18589  9285  6189  4641  3713  3094  2652  2321  2063  1856  928  619  464  371  309  265  232  206  186  1  5  m  20661  108000 sec  10318  52119  "  6877  34539  "  5157  25851  "  4126  20661  "  3438  17209  "  2947  14746  "  2578  12900  "  2292  11465  "  2063  10318  "  1031  5157  "  688  3438  "  516  2578  "  413  2063  "  344  1719  "  295  1473  "  258  1289  "  229  1146  "  206  1031  "  12 .. .Topcon Total Station Accessories Pack (Tamrac digital camera bag) Prism Topcon FC-100 Data Collector Topcon AD-9B AC/DC Converter Output DC12v 1000... target at the peak of the triangle in the sight Focus the target with the focusing knob from Topcon GTS 230 series manual You may want to check for parallax by shifting your eye slightly when... unless you need to go further or make adjustments Assumes you'll use the PDA to record data Topcon GTS 230 Series hardware manual Assumes you're not using the PDA, and also provides information